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Magnetic reconnection is a fundamental process in solar system and astrophysical plasmas, through which stored magnetic energy associated with current sheets is converted into thermal, kinetic and wave energy. Magnetic reconnection is also thought to be a key process involved in shedding internally produced plasma from the giant magnetospheres at Jupiter and Saturn through topological reconfiguration of the magnetic field. The region where magnetic fields reconnect is known as the diffusion region and in this letter we report on the first encounter of the Cassini spacecraft with a diffusion region in Saturn’s magnetotail. The data also show evidence of magnetic reconnection over a period of 19 h revealing that reconnection can, in fact, act for prolonged intervals in a rapidly rotating magnetosphere. We show that reconnection can be a significant pathway for internal plasma loss at Saturn. This counters the view of reconnection as a transient method of internal plasma loss at Saturn. These results, although directly relating to the magnetosphere of Saturn, have applications in the understanding of other rapidly rotating magnetospheres, including that of Jupiter and other astrophysical bodies.

Mercury's flux transfer event (FTE) showers are dayside magnetopause crossings accompanied by large numbers (≥10) of magnetic flux ropes (FRs). These shower events are common, occurring during 52% (1,953/3,748) of the analyzed crossings. Shower events are observed with magnetic shear angles (θ)from 0° to 180° across the magnetopause and magnetosheath plasma βfrom 0.1 to 10 but are most prevalent for high θand low plasma β. Individual FR duration correlates positively, while spacing correlates negatively, with θand plasma β. FR flux content and core magnetic field intensity correlate negatively with plasma β, but they do not correlate with θ. During shower intervals, FRs carry 60% to 85% of the magnetic flux required to supply Mercury's Dungey cycle. The FTE showers and the large amount of magnetic flux carried by the FTE‐type FRs appear quite different from observations at Earth and other planetary magnetospheres visited thus far. Any planet with an interior dynamo will interact with the outward streaming stellar wind and likely form a magnetosphere. The magnetopause is a boundary between the shocked solar wind and planetary magnetic field, which can prevent most of the solar wind from directly entering into the magnetosphere. The multiple X‐line reconnection that frequently occurs in the magnetopause creates helical magnetic fields that are termed magnetic flux ropes (FRs) about which open and interplanetary magnetic fields drape. FTE‐type FRs generally have magnetic field lines with one end embedded in the solar wind and the other end connected to the planet through the magnetospheric cusp. The investigation of FTEs in Mercury's magnetosphere is of particular interest because they often occur in large numbers with extremely small temporal spacing, i.e., FTE showers, that are not seen elsewhere. We find that the properties of the FTE‐type flux ropes in these showers depend upon plasma βin the magnetosheath and the magnetic shear angle across the magnetopause. The magnetic flux carried by these flux ropes dominates magnetic flux transfer between Mercury's dayside and nightside magnetosphere. These new results may contribute significantly to our understanding of solar wind‐magnetosphere‐exosphere coupling at Mercury. Flux transfer event (FTE) showers (≥10 flux ropes in a magnetopause crossing) are prevalent when shear angle is large and plasma βis smallFTE‐type flux rope duration, spacing, core field, and flux content during shower events are shown to depend upon shear angle and plasma βFTE‐type flux ropes in shower events carry between 60% and 85% of the magnetic flux required to supply Mercury's Dungey cycle